Photographic gelatin layer containing a n-acylated amino acid



UNITED STATES PATENT OFFICE PHOTOGRAPHIC GELATIN LAYER CON- TAINING AN-ACYLATED AMINO ACID Donald "R. Swan, Rochester, N. Y., assignor toEastman Kodak Company, Rochester, N. Y., a

corporation of New Jersey No Drawing. Application Mai-chi, 1940, SerialNo. 322,805

7 Claims.

This invention relates to photographic lightsensitive materials, such assensitized film, plates, and paper, comprising layers in which sensitivesilver salts are suspended or dispersed in gelatin or other suitablevehicle, and optionally comprising other layers as well. Moreparticularly, it

relates to the use of certain agents to facilitate the spreading ofgelatino-silver-halide layers and, in fact, the spreading of any gelatinor other hydrophilic colloid layers which are deposited from apredominantly aqueous medium and used in such photographic materials.

My invention perhaps finds its greatest usefulness in the manufacture ofphotographic film in which a sensitive gelatin emulsion layer is appliedto the film base, set by chilling, and then, without drying, isovercoated with a protective gelatin layer, the sensitive gelatinemulsion layer containing such a spreading agent. The general process ofcoating film base with a sensitive gelatin emulsion layer, setting bychilling, and overcoat-ing with a protective gelatin layer, is fully setforth in U. S. Patent No, 1,699,349 of'William B, Dailey.

If a sensitive gelatino-silver-halide" emulsion is coated on a film base(which has usually first been coated with a thinlayer or sub-stratum ofgelatin or other colloid and dried) without the addition of a suitablespreading agent, difficulty is experienced in that the emulsion willspread unevenly. Moreover, i the emulsion, while still in a wet, chilledcon ion, is overcoated with a protective gelatin coatin air bubbles formbetween the emulsion layer and the protective layer. Either of thesedefects, of. course, greatly impairs the quality of the photographicfilm.

It has, therefore, been customary in the art to add certain agents,such, for instance, as saponin, to the sensitive emulsion in order toavoid these defects as far as possible. Saponin has surfaceactiveproperties, and not only acts as a spreading agent for gelatin, but bysome mechanism not clearly understood, it prevents the formation of airbubbles between the gelatin layers .when a wet, chilled gelatin emulsionlayer containing the proper concentration of saponin is overcoated witha warm gelatin solution.

However, saponin, being a naturally occuring material of vegetableorigin, is of varying quality, and synthetic agents are to be preferredbecause of their more constant and controlled properties. Because of itsvarying quality, some batches of saponin may cause an increase in fog ora decrease in sensitivity in the sensitive emulsion, and in some casesmay produce little or no improvement in spreading. This is true whetherthe saponin be employed in the emulsion layer or in the protectiveovercoating or other layer. 4

Other surface-active materials have been tried in place of saponin, butmany of them, while they may act to some extent as spreading agents forgelatin, have been found to be entirely ineffective for preventing theformation of air bubbles when a wet, chilled gelatin emulsion containingthem is overcoated with a warm gelatin solution-and many of them areobjectionable from the standpoint'of fogging or desensitizing theemulsion.

I have found a class of surface-active compounds which are not onlyexcellent spreading agents for gelatin and other hydrophilic colloidlayers which are deposited from a predominantly aqueous medium and usedin photographic films, plates, and paper, but which, when incorporatedin layers such as sensitive gelatin emulsions, are superior to saponinin the prevention of bubble formation when the wet, chilled emulsionlayer is overcoated with a warm gelatin solution or other hydrophiliccolloid of the type which is deposited from a predominantly aqueousmedium. These compounds are the water-soluble N-acylated aliphatic aminocarboxylic acids and their salts, in which the acyl radical is theradical of an acid selected from the group consisting of the aliphaticacids of from 8 to 18 carbon atoms and the alicyclic acids. In the termaliphatic amino carboxylic acids I mean to include not only the simpleamino-acids, but the polypeptides, whether they be preparedsynthetically or by the degradation of natural proteins. In the termsalts I mean to include not only the inorganic salts, such as the sodiumsalts, but the organic salts, such, for instance, as the ethanolammoniumsalts, the trimethylammonium salts, the trimethylol-methyl ammoniumsalts, and the methyldimethylol-methyl ammonium salts: that is to say,the salts formed with the organic bases ethanolamine, trimethylamine,amino trimethylol methane and 2-methyl 2-amino propanediol. Among thealiphatic amino carboxylic acids, I may mention, by way of example,glutamic acid, glycylglycine, glycylalanine, and the mixtures ofPolypeptides and/or simple amino acids obtained by the hydrolysis ofproteins, for instance, casein, gelatin, and zein. Among the aliphaticacids of from 8 to 18 carbon atoms and the alicyclic acids I maymention, by way of example, lauric, myristic, pelargonic, oleic,ricinoleic, naphthenic, abietic and hydroabietic acids, and the mixtureof acids obtained from coconut oil. The preparation of N-acylatedaliphatic amino carboxylic acids and their inorganic salts is describedin U. S. Patents 2,015,912 of F. Sommer, 2,063,987 of H. Dreyfus, and2,113,819 of N. B. Tucker, and in British Patents 425,370 and 435,481.The organic salts may be prepared by dissolving the sodium salt of theN-acylated aliphatic amino carboxylic acid in water, precipitating'thefree N-acylated aliphatic amino carboxylic acid by means of 1:1hydrochloric acid, separating by decantation and redissolving in watercontaining the organic base. The salt is obtained as a gummy material byevaporation of the liquid in vacuo at 50 C.

These N-acylated aliphatic amino carboxylic acids or their salts may beincorporated in the sensitive gelatin emulsion at any point in itsmanufacture such that they will be present during its coating, in theproportion of from 0.001 to 0.5 part of spreading agent per 100 parts byweight of wet emulsion. This gives a spreading agent content of 0.01% to5% in the dried emulsion layer. They have not detrimental effect uponthe photographic properties of the emulsion, but, on the contrary,improve them. It is believed that the property of the spreading agentwhich prevents the formation of air bubbles when a wet, chilled gelatinemulsion is overcoated with a warm gelatin solution, also tends toprevent the formation of air bubbles, repellent spots, etc., on thesurface of a sensitive emulsion containing such a spreading agent, whenthat emulsion, coated on a film, plate, paper, etc. is immersed in adeveloper.

As above pointed out, the N-acylated aliphatic amino carboxylic acids ortheir salts, above defined, may be used in any one or more of thecolloid layers used to build up a photographic sensitive element upon abase such as film, glass, paper, etc., which layers consist of gelatinor other hydrophilic colloid which is deposited from a predominantlyaqueous medium, 1. e., a medium used as the solvent for such materialsin which water predominates, the remainder of the medium contributing togive a good dispersion of the colloid. If two superposed colloid layersare present, either, neither or both of which may be photographicallysensitive, the spreading agent may be used in either layer or in bothlayers. However, where a wet, chilled, light-sensitive gelatin orsimilar layer is to be overcoated with a warm solution or emulsion ofgelatin or similar material, the presence of the spreading agent in thewet, chilled layer is essential for preventing the formation of airbubbles between-the layers. Examples of such hydrophilic colloids otherthan gelatin, which are useful as layers in photographic films, plates,paper, etc., are the Water-soluble cellulose derivatives such as wellhydrolyzed cellulose acetate (described in U. S.

Patent No. 2,110,491 of Sale) and cellulose esters of hydroxymonocarboxylic acids, such as lactic or glycollic, and salts ofcellulose esters of dicarboxylic acids, such as phthalic- (described inU. S. Patent No. 2,127,573 of Sheppard and U. S. Patent No. 2,127,621 ofStaud), as well as polyvinyl alcohol and hydrolyzedpolyvinyl acetate(described in applications of Wesley G. Lowe, Serial Nos. 318,559 and318,560, filed February 12, 1940) and water-soluble polyvinyl acetals(described in an application of Charles R. Fordyce, Serial No.

221,584, filed July 27, 1938, Patent No. 2,211,323). When colloids otherthan gelatin are used, it may be desirable to coat them at differenttemperatures. 4

In the claims appended hereto, where a hydrophilic colloid depositablefrom a predominantly aqueous medium is referred to, it will beunderstood to mean any hydrophilic colloid which can be deposited from amedium which is predominantly aqueous, the remainder of the medium beingan organic solvent which contributes to the dispersibility of thecolloid;'examples of such organic solvents for this purpose are acetone,ethyl alcohol, ethylene glycol, monoacetin and pyridine,

What I claim as my invention and desire to be secured by Letters Patentof the United States is:

1. Photographic sensitive material comprising a layer of a hydrophiliccolloid depositable from a predominantly aqueous medium, said layercontaining from 0.01% to 5% of a compound selected from the groupconsisting of the water-soluble N-acylated aliphatic amino carboxylicacids and their salts, in which the acyl radical is the radical of anacid selected from the group consisting of the aliphatic acids of from 8to 18 carbon atoms and the alicyclic acids.

2. Photographic sensitive material comprising a gelatin layer containingfrom 0.01% to 5% of a compound selected fro-m the group consisting ofthe water-soluble N-acylated aliphatic amino carboxylic acids and theirsalts, in which the acyl radical is the radical of an acid selected fromthe group consisting of the aliphatic acids of from 8 to 18 carbon atomsand the alicyclic acids.

3. Photographic sensitive material comprising a base and two superposedgelatin layers, in which the gelatin layer nearer the base contains from0.01% to 5% of a compound selected from the group consisting of thewater-soluble N-acylated aliphatic amino carboxylic acids and theirsalts, in which the acyl radical is the radical of an acid selected fromthe group consisting of the aliphatic acids of from 8 to 18 carbon atomsand the alicyclic acids.

4. Photographic sensitive material comprising a base, a photo-sensitivegelatin emulsion layer and a gelatin overcoating on the emulsion, inwhich the photo-sensitive gelatin emulsion layer contains from 0.01% to5% of a compound selected from the group consisting of the water-solubleN-acylated aliphatic amino carboxylic acids and their salts, in whichthe acyl radical is the radical of an acid selected from the groupconsisting of the aliphatic acids of from 8 to 18 carbon atoms and thealicyclic acids.

5. Photographic sensitive material comprising a gelatin layer containingfrom 0.01% to 5% of the sodium salt of the N-lauroyl compound ofthehydrolysis products of casein.

6. Photographic sensitive material comprising a gelatin layer containingfrom 0.01% to 5% of the sodium salt of the N-lauroyl compound of thehydrolysis products of gelatin.

7. Photographic sensitive material comprising a gelatin layer containingfrom 0.01% to 5% of the sodium salt of the N-lauroyl compound of thehydrolysis products of zein.

DONALD R. SWAN.

